[PATCH] D105902: [RISCV] Fix the neutral element in vector 'fadd' reductions

[Fraser Cormack via Phabricator via llvm-commits]

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Using positive zero as the neutral element in 'fadd' reductions, while
it generates better code, is incorrect. The correct neutral element is
negative zero: 0.0 + -0.0 = 0.0, whereas -0.0 + -0.0 = -0.0.

There are perhaps more optimal lowerings of negative zero avoiding
constant-pool loads which could be left as future work.


Repository:
  rG LLVM Github Monorepo

https://reviews.llvm.org/D105902

Files:
  llvm/lib/Target/RISCV/RISCVISelLowering.cpp
  llvm/test/CodeGen/RISCV/rvv/fixed-vectors-reduction-fp.ll
  llvm/test/CodeGen/RISCV/rvv/vreductions-fp-sdnode.ll

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